Physicochemical Studies on Dusts

Brown, James (1956) Physicochemical Studies on Dusts. PhD thesis, University of Glasgow.

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1. The history of pneumoconiosis is outlined. The various theories advanced to explain silicosis are stated and their validity discussed. This allows the problems chosen for research to be seen in relation to other problems in this field, and provides a general background to the research. 2. The phenomenon of the "ageing" of siliceous dusts, whereby the rate of solubility of the dusts appears to decrease with storage time, has been investigated. The effect of the preparative processes (acid-extraction, washing, and drying), the humidity and gaseous nature of the storage atmosphere, and the absorption of carbon dioxide by the solvent have been examined. The nature of the surface of the dusts after grinding has also been studied. As a result of the experiments it was concluded that the decrease in solubility of siliceous dusts on storage is the result of the following factors:- (a) A gradual change in the nature of the modified surface (produced by grinding) from an amorphous to a more crystalline form, of lower solubility. (b) The humidity of the storage atmosphere and the adsorption or loss of water by the dusts. (c) The absorption of carbon dioxide by the solvent. The relative importance of each factor varies, and depends on the physical characteristics, (e. g. particle size, crystallinity) of the dust involved. 3. The physical properties of silica (SiO2 - fibrogenic) and rutile (TiO2 - non-fibrogenic) have been compared. The following results were obtained:- (a) The solubility of rutile at pH 7.5 (the pH of the lung fluids) is so low as to be outwith the sensitivity of the reagent used (i.e. < 1 part in 10e6). Silica has a readily measurable solubility at this pH. (b) The existence in rutile dusts of a disturbed surface layer of higher solubility than the core, analogous to the "disturbed layer" of quartz, was not detected. (c) Rutile and quartz were shown to adsorb to same types of dyestuffs (i.e., basic). (d) Rutile adsorbs three to four times as much basic dye as does quartz. These results indicate that simple adsorption of materials from the lung fluids plays at the most a small part in the production of silicosis. They provide further evidence in support of the "solubility theory" of silicosis. 4. A method for the synthesis of small crystals of pure (parts has been developed. The development of this method is described. Its use for the investigation of the effect of trace impurities on the physical and fibrogenic properties of quarts is discussed.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Physical chemistry, Inorganic chemistry
Date of Award: 1956
Depositing User: Enlighten Team
Unique ID: glathesis:1956-79172
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 31 Mar 2020 09:09
Last Modified: 31 Mar 2020 09:09

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